The invention disclosed herein is generally related to alpine, or downhill, skis. More particularly, this invention is related to alpine skis having means for varying the flexibility, or stiffness, of the ski.
The performance characteristics of modern alpine skis are well known to depend heavily on the stiffness, or flexibility, of the ski with respect to bending in the vertical plane. Moreover, such characteristics are known to depend on the flexibility along different longitudinal sections of the ski. In this regard, the alpine ski is generally described as being divided into three longitudinal sections, known as the shovel, or front section, the center section, and the tail, or rear section. Skis are fabricated with varying degrees of stiffness along these sections to meet particular requirements. For example, slalom skis are usually fabricated with shovel and tail sections which are relatively stiff, as a ski with firm end sections can be turned more quickly than a ski with soft end sections. Giant slalom skis, for which smooth tracking at high speeds is a desirable characteristic, generally have softer end sections. Mogul skis are designed to be turned quickly but must also be sufficiently flexible to absorb shocks comfortably, and are accordingly designed with a relatively soft flex. Powder skis are more flexible throughout, and are often designed as very soft giant slalom skis.
The distribution of the ski flexibility along the length of the ski is referred to as the flex pattern of the ski. It is known that relatively small changes in the flex pattern can have marked effects on the overall ski performance. The flex pattern is ordinarily determined using a standardized analytical stiffness test, in which the deflection of the ski in response to a predetermined force is measured while the ski is mounted on two support points spaced approximately 30 centimeters apart. The test is conducted, for example, at five-centimeter intervals along the length of the ski. The resulting measurements can be plotted graphically as a function of position along the ski, so that the overall flex pattern can be readily visualized and correlated with ski performance.
Corrections or alterations to the flex pattern of a ski are normally made by changing the thickness of the ski at various points, or by altering the modulus or thickness of the load-bearing surface elements of the ski.
It has been previously known to employ tensioning devices in alpine skis to selectively control the overall flexibility of the ski. However, the previously known devices are ineffective to allow selective adjustment of the flexibility along different sections of the ski. Also, various of the previously known devices have been impractical to adjust in the field, or have included adjustment mechanisms which are undesirable in that they protrude in an unwieldy manner above the surface of the ski.